JPS60117165A - Detection of vector magnetic field by two-dimensional magnetic sensor - Google Patents

Abstract

PURPOSE:To raise the detection sensitivity of a magnetic field, by scanning four pairs of orthogonal pairs of 16 collectors, which are arranged in a split state at equal intervals so as to be made concentric around an emitter base region, in a time sharing manner to calculate azimuth angles and calculating the azimuth angle of a magnetic field on the basis of one azimuth angle among the calculated ones. CONSTITUTION:The two-dimensional magnetic sensor of a transistor is constituted by arranging 16 collectors C1-C16 at equal intervals in a state concentric around a base B and emitter E region. Therefore, when two pairs of certain specific orthogonal collector pairs are taken to an arbitrary magnetic field directions, the azimuth angle theta of a magnetic field comes to 33.75<=theta<=56.25. Outputs of four pairs of orthogonal collector pairs are scanned in a time sharing manner to calculate azimuth angles and the azimuth angle of the magnetic field is calculated on the basis of the output of a pair satisfying this condition. By this method, the detection sensitivity of a magnetic field is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting a vector magnetic field using a two-dimensional magnetic sensor having a plurality of collector pairs.

In recent years, a transistor two-dimensional magnetic sensor having a plurality of collector pairs has been developed, and research is underway to utilize this sensor in encoders and other vector magnetic field detection systems.

FIG. 1 is an explanatory plan view of a transistor two-dimensional magnetic sensor, and FIG. 2 is an explanatory cross-sectional view showing its basic operation. An overview of the magnetic sensor will be explained based on these figures. In the same figure, (El is the emitter, Mon) is the base, (C1) ~
(C4) is 0 vector. This sensor (1) is a Brainer type NPN) transistor with four collectors (Ct-) to (C4). Electrons (e-) injected from the base (Bl) region diffuse through the base (Bl) region. At this time, the collector (CI) and (Ct) are When the base (81) is placed in There is no current difference between the collectors (Cs) and (C4).

However, when the magnetic field H exists in the y direction, more electrons (e receive a force in the X direction due to the Lorentz force, move as shown in the magnetic field, and reach the collector CCI) more often. As a result, a current difference occurs between both collectors (C1) and (Ct). Since this current difference is proportional to the magnetic field H, the value of the magnetic field H can be known by detecting this current difference.

Briefly, the method for detecting the vector magnetic field will be explained. The magnetic field H felt by the magnetic sensor is decomposed into two-way components, and H
If we consider x and ay separately, collector bear (Cs),
(C4) outputs an output proportional to Hx, and the collector pair C
C+), (, Ct) output an output proportional to Hy.

Output t”C of collector pair (Cs), (“4”)
Assuming that the output cy of the xs collector pair CC8) and (Ct) is, the azimuth angle θ of the magnetic field is.

θ= Arczan (Cy/cz) '...(1) So, the magnitude of the magnetic field H is H==r below? ...(2) I can't stand it.

The magnetic sensor is used as a sensor in a vector magnetic field measuring device shown in FIG. 6 based on the principle described above. In the figure, (2) is a sensor drive circuit;
(3), (4) are current-voltage converters, (5) are A/
A D converter, (6) an F1 microcompounder, and (7) an output display section. The magnetic sensor (1) is driven by a sensor drive circuit (2), and each collector (CI~
A current proportional to the magnitude of the magnetic field flows through C4).

Then, each collector pair (“11 CJ * (Cs
*The current difference in C4) is determined by the current-voltage converter (3).
, (4) converts it to voltage, and converts it to voltage using A/D converter (
5) to the microcomputer (6). The microcomputer (6) performs the arithmetic processing of equations (1) and (2) above, and displays the azimuth angle θ and magnitude H of the magnetic field on the output display section (7).

However, in the above measurement method, the minimum value of the magnitude H of the magnetic field that maintains the accuracy of the indicated value of the azimuth angle θ changes depending on the azimuth angle θ.
It was found that while the accuracy was up to 1 (Oerated) in H, the accuracy was only up to 1 (Oerated) in the vicinity of θ-8 = 90゛. This can be explained by the following reason.

When the magnitude of the magnetic field H is applied to the magnetic sensor at an azimuth angle θ, the collector pair in the x direction feels a magnetic field of He'sθ (CCx), and the collector pair in the y direction feels a magnetic field of Hsinθ CC' . However, when the detection sensitivity of the magnetic sensor is α1 (Oersted), He'l
The relationship of lθ≧0.1 and HBinθ≧0.1 is H
and θ is required. Based on this relationship, FIG. 4 shows the magnetic field detection sensitivity limit H8 with respect to the azimuth angle θ.

As shown in the fourth characteristic diagram, near θ=45° where the values of C and Cry are equal, 0.15 (Oersted
), whereas the vector magnetic field can be measured up to θ=80°
, 1.0 in H8 near 1'0° (Oers-zed
) I can't do L.

In other words, in the conventional measurement method using a two-dimensional magnetic sensor,
As the azimuth angle θ of the magnetic field approaches 0° and 90°, the detection sensitivity of the vector magnetic field deteriorates.

The present invention was invented in view of the above situation, and provides a vector magnetic field inspection method using a two-dimensional magnetic sensor that can detect vector magnetic fields with high sensitivity regardless of the azimuth of the magnetic field. This is what we provide.

The method for detecting a vector magnetic field according to the present invention is to construct a collector of a two-dimensional magnetic sensor and time-divisionally scan four orthogonal collector pairs arranged in sub-divisions at six concentric circular intervals KL, centering on the vine pace region. The azimuth angle by each orthogonal collector pair is calculated, and the obtained azimuth angle θ(Nl
(N=1 to 4), 3-5Zda≦10(g)1≦5
Select the azimuth angle θ (to) indicated by the collector pair that corresponds to 6=25'. Then, the magnitude H of the magnetic field is determined based on the output of the collector pair at this time, and the azimuth angle θ (goods) is determined.
The azimuth angle θ of the magnetic field is determined by adding the rotation angle α of the axis of the collector pair to .

Next, an embodiment of the present invention will be described based on the drawings.

FIG. 5 is an explanatory plan view of a two-dimensional magnetic sensor according to an embodiment of the present invention. In the same figure, the collector (C8~”
16 +s) are arranged concentrically at equal intervals around the vine. That is, each collector has 2
2.5 pieces are evenly spaced. Therefore, if we take two specific orthogonal collector pairs with respect to any magnetic field direction, the azimuth angle of the magnetic field will necessarily be in the region of 4f±11.25' in the orthogonal frame system of the collector pair. be. When the azimuth angle is within the range of 3575≦θ≦56.25,
As shown in Figure 4, the detection sensitivity is 0.18 (Oers
ted) and good. Taking advantage of this feature, 5 & 75≦・110) 1≦56 out of 4 pairs of orthogonal collector bears.
It is good to use the angle θ (Nl) as data by the collector bear which shows the value of 21. In Fig. 4, if there is a magnetic field H in the direction shown, the collector bear (Cs, C1,
) and (Cv, Cts) based on the orthogonal coordinates (X.y) is adopted, and the rotation angle α (to) of the axis of the collector bear is added to this azimuth angle θN. If O, 18 (Oer
It is possible to detect vector magnetic fields down to minute magnetic fields (gted).

By the way, the magnetic sensor has 16 collectors (Cz~
With C8.), the number is four times that of the one shown in FIG. 1, and if a constant current is caused to flow in the same driving method as the conventional method, the collector current becomes relatively 1/4. ip,
As shown in FIG. 6, the sensitivity decreases when the collector current is small. In Fig. 6, IC is the current flowing through one collector when the magnetic field is φ.Therefore, in the present invention, four sets of orthogonal collector bears (C! Ce "s r Cta)・(Ct・"Io
−C・・Cl4)・(Cs * CH−Ct + C
+s ) and (C4+ C+s −Ca * Cts
) are sequentially switched and driven, and outputs are extracted one set at a time to calculate the azimuth. In this way, by increasing the drive current supplied to each collector, detection sensitivity is increased.

Next, a measuring device employing the detection method according to this embodiment will be constructed based on the block diagram of FIG. 7 and the flowchart of FIG.
I will explain.

In Fig. 7, at φ, (21, (s), (s), (6
) and (7) are the same as those shown in the diagram of FIG. 6 with the same reference numerals, α is the magnetic sensor shown in FIG. 5, and (2) is the collector scanner.

The magnetic sensor αp is driven by a sensor drive circuit (2), and N- (N'=1) channels are opened by a collector scanner (2). For example, if we toss the first channel with collector bears (C, , C, C, , C), current will flow only through these collector bears, and their output will be the current -
The signal is supplied to a converter (5) via a voltage converter (3), converted into a digital value, and after 'fc' is input into a microcomputer (6). Microcomputer 7
(6) The azimuth angle θ(1) and the magnitude H(1) of the magnetic field in the first channel are calculated based on the above (0 formula and (2) formula) and stored. 2nd channel (CH+ C16-
Co*C14)% 3rd channel (c,, cm-C
y+C□), and the fourth channel (C4sCst C
4sCst) At t, the magnetic field size H and azimuth θ(1'4 (N
= 1 to 4) and memorize 0, and of the azimuth θN, θ indicates 33.75≦l#(Nil≦56.2
Select (N) and select HH.

Next, 1 is added to this azimuth angle θ (value) and the rotation angle α (value) of the shaft of the collector bear, and this is taken as the azimuth angle θ of the magnetic field.

As for the magnitude H of the magnetic field, use the above H□ as is. The magnitude H of the magnetic field and the azimuth θ determined in this way are displayed on the output display 5 (7).

As explained above, the present invention provides four pairs of orthogonal coordinates and calculates the azimuth angle respectively, and the azimuth angle θ) is '33:;7
The sensitivity α18 (Oerate
d) The unmeasurable angular region is also shown. The conventional method is H = 1.0 (Oarstad) or less,
1θ-90°1? , 1θ-180°1〈the, and 10
Comparing this with the fact that measurement was impossible in the region of 1<5', it can be concluded that the effect of the present invention is significantly greater than φ.

In addition, if current is supplied to all collectors at the same time, and the sensitivity is 04 mV/Gauss, then
According to the present invention, the sensitivity is 1.4''/Ga□3 and &5 times the same as above, and the circuit configuration is also simpler than in the above case.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a conventional transistor two-dimensional magnetic sensor, Fig. 2 is a cross-sectional view showing its basic operation, and Fig. 3 is a plan view of a conventional transistor two-dimensional magnetic sensor.
FIG. 4 is a block diagram of a vector magnetic field measuring device using the magnetic sensor, FIG. 4 is a characteristic diagram showing the magnetic field detection sensitivity limit with respect to azimuth angle, and a plane explanation of a two-dimensional magnetic sensor according to an embodiment of the present invention by Company 51. 6 is a characteristic diagram showing the difference in sensitivity depending on the collector current, FIG. 7 is a block diagram of a vector magnetic field measuring device that employs a detection method according to an embodiment of the present invention, and FIG. 8 is a characteristic diagram showing the difference in sensitivity due to collector current. 0 is a flowchart showing the operation of the device (1)...Conventional two-dimensional magnetic sensor, (2)...Sensor drive circuit, (3)...Current-voltage converter, (5)
... Φ controller 7 (-ta, (6) ... microcomputer, (7) ... output display section, turtle F ... 2 of the present invention
Dimensional magnetic sensor, (2)...Collector scanner. Agent Patent Attorney Sanro Kimura 1st rM 2nd f! I Akane No. 5 - No. 6rM Ishitake Kazuto Figure 8 Procedural Amendment (Spontaneous to the Commissioner of the Japan Patent Office, April 138, 1981) 1. Indication of Case Patent Application No. 58-224565 2. Title of Invention 2-dimensional Detection method of vector magnetic field by magnetic sensor Basic name (412) Nippon Koukan Co., Ltd. 4, Agent "Brief explanation of drawings" columns El1 and 7, Contents of amendment (11 Specification, page 4, line 2 - Line 3: “Each collector...
...flows. ” and “each collector pair (Ct, C5)
-CCsIC4) current difference is proportional to the magnitude of the magnetic field. ” he corrected. (2+ specification page 11 line 6 r (31J r 13
1. (4) Correct as J.

Claims (1)

[Claims] The collector of the two-dimensional magnetic sensor is divided into 16 parts concentrically arranged at equal intervals around the emitter base region, and the four orthogonal collector pairs are scanned in a time-division manner, and the azimuth angle of each orthogonal collector pair is calculated. , among the obtained azimuth angles θ(N) (N=1 to 4), ss, y, f'≦1
The azimuth angle θ(
), and the azimuth angle of the magnetic field is determined based on the selected azimuth angle θ.